CACHE MEMORY

The computers today have cache memory that save the time the processor would use to fetch data from the main memory (RAM). This cache memory now facilities speedy movement of data / instructions from RAM to the processor. It is invented to overcome the difference in the speed of the processor and the RAM, which is extremely high compared to the access time of the main memory. The slow speed of the RAM had been the major causes of poor performance of CPU.

SECONDARY STORAGE UNIT
the secondary storage unit is also called Auxiliary Storage unit. This supplements the limited main memory of the CPU. Examples are magnetic disks, relevant programs and data re moved from Secondary Storage onto the RAM (primary storage). Secondary Storage is not like Primary storage that holds data permanently even when computer is short down. Secondary storage devices are:

Magnetic tape: this device is used in main frame computer for storing large volume of data. it can also be used in personal computer (PC). Magnetic tape has one side coated with iron oxide which can be magnetized. Data stored on the tape can be read or erased by a magnetic tape drive. Magnetic tape is accessed and recorded sequentially.

The common Magnetic tapes are:

REEL-TO-REAL, CARTRIDGE TAPE, CASSETTE TAPE AND DIGITAL AUDIO TAPE. magnetic tape has long term storage and Re- Usability features. That is, it can store data for long time and can be used repeatedly without loss of  data. it requires no complex software to operates it.

Magnetic Disks

These provide random and sequential processing capability because of the dual capability, magnetic disc storage is commonly used A magnetic storage stores data in a series of magnetized spots on the flat surface of one or more disks.

Types of Magnetic Disks.

• Floppy Disk
• Hard Disk